A conventional gas turbine engine includes a compressor for compressing a flow of ambient air, a combustor for mixing the compressed flow of ambient air with a flow of fuel to create a flow of hot combustion gases, and a turbine that is driven by the hot combustion gases to produce mechanical work. The turbine may drive a load such as a generator for electrical power. Various strategies are known for increasing the amount of power that a gas turbine engine may be able to produce. One method of increasing the power output is by cooling the ambient air flow upstream of the compressor. Such cooling may cause the air flow to have a higher density, thereby creating a higher mass flow rate into the compressor. The higher mass flow rate into the compressor allows more air to be compressed so as to allow the gas turbine engine to produce more power. Moreover, cooling the ambient air flow generally may increase the overall efficiency of the gas turbine engine in hot environments.
Various systems and methods may be utilized to cool the ambient air flow entering the gas turbine engine. For example, inlet air systems with one or more heat exchangers may be used to cool the ambient air flow through latent cooling or through sensible cooling. Such heat exchangers often may utilize a wetted media pad to facilitate the cooling of the ambient air flow. These wetted media pads may allow heat and/or mass transfer between the ambient air flow and a coolant flow such as a flow of water. The ambient air flow interacts with the coolant flow in the wetted media pad for heat exchange therewith. The airflow passages through such wetted media pads are intended to provide effective water evaporation and mixing of the flow of ambient air with the water vapor from the flow of water. As the air velocity increases, however, water shedding may occur. Specifically, airborne water droplets may coalesce in a downstream inlet duct and/or flow into the compressor. Such water droplets may cause blade abrasion and other types of damage.
Current evaporative cooling media replacement intervals may range from about one to five years or about 18,000 hours of operation depending upon the usage, the air quality, the water quality, and other types of parameters. Media degradation over time results in a reduction in overall gas turbine efficiency. The costs and the downtime require to replace the media, however, must be balanced with this possible reduction in efficiency.